Lewis, who played in the same AAU program as Stevens and has known him for years, said the offensive and defensive systems the Celtics are running appear to be very similar to what the Bulldogs ran under Stevens during his tenure as head coach there.

“It’s a lot of the same stuff with minor tweaks,” Lewis said.

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On the one hand, it makes sense that Stevens is running the kind of schemes that made him successful and, in turn, helped him land the Celtics job this past offseason.

On the other hand, it might come as a surprise to some Celtics fans that their team, which plays the Cleveland Cavaliers Friday at TD Garden, is employing schemes used by a private mid-major school in Indianapolis that became a Cinderella story when it reached consecutive national championship games in 2010 and 2011.

Ever the strategist, Stevens wouldn’t go into much detail about his schemes, but he said the ones he has in place in Boston are “probably very different” from what he was using at Butler.

“Still the same basic ideas that lead to winning,” Stevens said. “Just a lot different ways of getting there, just from the standpoint of the way we’re playing defensively . . . and some of the things we’re doing offensively. And some of that is an adjustment to the longer game and the shorter [shot] clock.”

According to Lewis, the Bulldogs ran a ball-screen motion offense with a ton of set plays under Stevens. On defense, he said, the idea was “21-D,” which meant they wanted to “guard you extremely hard from 21 feet and in.”

Lewis also said that most of what Butler ran under Stevens was based, at least in part, on what NBA teams were running.

“He picked up a lot of stuff from the NBA,” Lewis said. “When we were on the road playing on a Saturday, he was in a hotel room on a Friday night watching an NBA game. And he’d come to breakfast Saturday with a new play that he thought could work.

“Our defensive system — from how we guarded ball screens and how we rotated — is really similar to what some NBA teams do.”

The Bulldogs were relentless on defense under Stevens, and Lewis is seeing the same kind of aggression with the Celtics.

“They’re really guarding people,” he said. “He’s got them playing so hard. He’s got them playing together. They’ve been fun for me to watch.”

Shooting for more

Jared Sullinger is shooting a less-than-crisp 26 percent from 3-point range (9 of 34), even after he sank two of three from long distance in the Celtics’ loss to Memphis Wednesday.

“I don’t think he shoots enough of them,” Stevens said. “And I’ve said that all year.”

Indeed, Stevens has recited that line many times, publicly and to Sullinger.

“He constantly tells me to take the open shot,” Sullinger said. “And he’s always in my ear about shooting the ball. Sometimes I feel comfortable shooting, sometimes I don’t.

“I think it’s just the mind-set. I’ve got to understand if they are going to give me that shot, I’m going to take it.”

But it is a dilemma, because the 6-foot-9-inch Sullinger’s bread-and-butter shots usually come around the rim.

“The first question you ask when you’ve got a guy who can make threes is, ‘Can you switch him?’ And you can’t switch him,” Stevens said. “There’s no plausible way to do that because he’s so good in the post.

“A lot of 3-point shooters aren’t very good post players. So if he can continue to develop that part of his game, that could really help us.”

Stevens said the shoot-the-3-pointer-if-you’re-open rule applies to the other big men, such as Vitor Faverani (9 of 24) and Kelly Olynyk (4 of 22), who have shown they can knock down shots from beyond the arc.

No place like home

The Celtics are an unimpressive 2-5 at home, but Stevens said their poor record at TD Garden has nothing to do with the atmosphere.

“Of all the atmospheres I’ve been in in the NBA — and I haven’t been here very long — this is by far my favorite,” he said.

Of course, such a response is to be expected, and it would be breaking news only if Stevens said anything to the contrary, such as liking another arena more.

“At the end of the day, we need to get better at home, we need to get better on the road, we need to become a better basketball team,” he said.